


Entanglement

by Kitchyy



Category: Supernatural
Genre: Alpha Dean, Alpha Sam, Alpha/Beta/Omega Dynamics, Alternate Universe - Canon Divergence, Beta Kevin, Bottom Castiel, First Time, M/M, Mating Bond, Mating Cycles/In Heat, Men of Letters Bunker, Omega Castiel, Season/Series 09, Team Free Will, Top Dean
Language: English
Status: Completed
Published: 2016-11-13
Updated: 2016-11-13
Packaged: 2018-08-30 18:06:05
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 8,870
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8543626
Author URL: https://archiveofourown.org/users/Kitchyy/pseuds/Kitchyy
Summary: It's about a month and a half into Cas being human when it hits, which doesn't make any sense because all the omegas Dean's ever known have a three month cycle. Dean's in the war room with Sam going over the details of a possible nest of vamps when this scent drifts into the room that makes Dean's mouth water."You baking something?" Dean asks.Sam crinkles his brow. "I've been sitting here with you for the last hour. So no."





	

**Author's Note:**

> I may have changed a few small things for Season 9 because Dean telling Cas he couldn't stay in the bunker was't very nice in my books. Also I really liked Kevin, so I'm keeping him'. 
> 
> Not mine, never will be, yadda yadda. No beta so all mistakes are mine, all mine. If you do catch something please let me know so I can fix it up.
> 
> Edit: November 13 - I fixed up some of my tags

In Dean's defense there was kind of a lot going on.

He knew that Cas' vessel was an omega. He had known it the moment Cas temporarily left Jimmy's vessel all those long years ago. The cool ozone and thunderstorm scent that Dean associated with Cas was gone and in it's place was the muted sweetness of mated omega. In the few times Cas had his mojo drained or stolen that same rich scent had returned, so when Cas called him saying he was human Dean knew on some lizard brain level that Cas in that body would be an omega. But Sam was next to dead, the angels were falling and eager to rip Dean and Sam into pieces, and there was the tiny problem of Ezekiel inhabiting his brother without his knowledge. So, yeah. Not exactly on his top list of priorities.

However crazy their situation was, priorities may have shifted slightly when Dean and Sam finally found Cas - with that sneaky April alpha bitch. Dean took one sniff of that apartment and fucking _knew_ he wasn't letting Cas out of his sight after that. Call it typical Alpha posturing. Call it trying to protect his newly human friend. Call it whatever the hell anyone wanted, Dean really didn't care.

It also didn't help that Cas smelled different now. Not like ozone but not like Jimmy either. It was soft and rich, like dark chocolate or baked goods, and it was definitely unmated. Dean took Cas into the bunker and didn't give a flying fuck what Ezekiel said. There was no way Dean was letting an unmated omega run around all over hell's half acre without any knowledge of what his smell did to other alphas. The asshole angel could go fuck himself, and Dean said it right to his face. Eventually the bastard folded, much to Dean's relief.

When Ezekiel (turned Gadreel – shoulda seen that one coming) finally fucked off with the help of Crowley of all people, Sammy wasn't the irreparable mess he was said to be.

Fucking angels. Just – just fuck the lot of them.

So now it's them in the bunker. Two alphas, a tablet translating beta and one omega, coming right up. Oh, and with just a small side of the world's in utter turmoil, have a nice day.

Dean knows Sam's scent, knows Kevin's too, and he's learning to integrate the musty leather and book smell of the bunker with them all wrapped in it, but now there's this delicious omega scent fogging up the halls that Dean isn't used to. He honestly doesn't have a lot of experience with omegas, Dean's always been partial to the betas. Their comforting smells always seem to remind him of what home should smell like and they're a lot less maintenance. Dean can keep a level head around them, and he likes that. Sure, he's had a fling or two with a cute omega here and there, but they always seem to come with baggage and Dean has that in spades all on his own.

Cas as a human is different than Cas as an angel. He seems more... well not fragile, the guy has some wiry strength hidden under those baggy clothes he's gravitated to wearing, but he's less imposing. He's easier to talk to in some ways and harder in others. It takes time to get used to him – get used to their new dynamic of them all teaching Cas what it really is to be human - indigestion, insomnia, muscle aches, smells and all.

Cas' scent is... to be honest it's damn distracting. Dean wants to tell him to get some suppressants or something, because Cas shouldn't smell so damn good all the time. It shouldn't make Dean want to press his nose to his hair and breathe deep. Of course, in typical Cas fashion he has absolutely no clue what he's doing with all that omega smell. He does his weird confused head tilty thing when some jackass alpha slides up to him when they're in the grocery store and tries to take him home. Raises his brows in confusion when someone tries to hit on him when they're out after a hunt in some backwater bar.

Dean is running interference like a champion and it's grating on his Every. Last. Nerve.

Sam isn't helping at all. The sasquatch shit just keeps giving Dean these looks, like he saw this coming a mile away and wants to sit back and watch the whole show with some popcorn and a beer. Dean wants to punch him in his stupid gigantor face when it gets bad. He knows it won't end well if he does, but he still thinks about it sometimes.

So Dean does the only reasonable thing he can think of. He changes up the bars they go to, makes sure Cas doesn't wander alone in the frozen foods section, even follows him into convenience stores. He stares down any idiot alpha knot brain who thinks they can just sidle up to Cas like he's theirs. Cas doesn't seem to notice a lot of the things Dean does, but sometimes Cas looks at him all head tilty and confused, like Dean is some puzzle he has yet to figure out.

When Cas is helping with a hunt is when it's the worst. Cas in that fake agent suit with that smell coming off him... it's like he's trying to be one of those independent, liberal omegas who don't need no alpha, thank you very much - and that would work, but only if he knew that's what he was giving off, but he doesn't. OK, so witnesses talk to him a lot better because of his scent, so what? Dean could get the same information, and there wouldn't be so much touching. Like a hand on Cas' arm for support. A brush of fingers across his hand when they want him to understand. The bold ones even try touching his neck and Dean can handle a lot of things, but not that. And of course Cas doesn't understand what they're doing, doesn't know when to end that arm grab or step out of reach and it's making Dean go just a tiny bit bonkers.

He starts changing up the soap in the bunker to that blocker stuff, leaves out super strong smelling cologne and does the laundry with the stinky detergent. Some of it works, at least a little but it's still there, permeating the air around Cas and all one would need to do is lean in and inhale and it's there.

And Dean has no idea how to mention this stuff to Cas. Has no clue how to say 'dude, you gotta get your scent under control' without sounding like some shitty old school knot head with a chip on their shoulder a mile wide. But he wants to. Oh, he really, really wants to.

It's about a month and a half into Cas being human when it hits, which doesn't make any sense because all the omegas Dean's ever known have a three month cycle. Dean's in the war room with Sam going over the details of a possible nest of vamps when this scent drifts into the room that makes Dean's mouth water.

"You baking something?" Dean asks.

Sam crinkles his brow. "I've been sitting here with you for the last hour. So no."

Huh. That's weird. So maybe Kevin? Dean looks over and finds him by the other table running his hands through his hair and doing a good job of trying to destroy his paperwork by glare alone.

Not Kevin then. So it's gotta be Cas making food, but its 9am and he hasn’t seen Cas do his walking dead impression towards the coffee machine yet. The smell keeps getting stronger and he notices Sam's nose twitch, then his eyes lift above and behind Dean and widen comically.

Dean turns to find Cas leaning on the doorway. He looks tired and sleep mussed, but his eyes are fever bright, his face is flushed and the smell. Oh god. It's coming from him.

Dean scrambles out of his chair and takes a step back.

"Cas?" Sam asks. "You feeling ok?" Which is a ridiculous question. Anyone who has a nose can smell that no, he isn't.

Cas presses his forehead to the doorway and groans. He's wearing a pair of Dean's old pajama pants and a robe that isn't completely done up so a thin strip of torso is catching the light where a sheen of sweat covers him. Dean wants to lick him, catch all the moisture from that body and make it his. Make Cas his.

And that's it. Dean officially can't do this. He's out. Done. Kaput.

Cas looks up and says "I think I have a fever."

A fever, right. Dean would give his left big toe for it to be a fever.

"Uh... I don't think that's it." Kevin clears his throat and goes to inspect Cas. He puts a hand on his forehead and Cas leans into it, rolling his body in a way that is definitely not sickly. Kevin sniffs a few times and Dean wants to run over there and tear him away from Cas, hide him away from the world until this rides out. "Cas, I don't think you have a fever. I think you're in heat."

Dean sneaks a look at Sam who is dutifully trying to breathe through his mouth out of respect. Dean tries to do the same thing, but fuck all the help it does. Now he can taste Cas on his tongue.

"In heat?" Cas questions, as if the thought had never even occurred to him. As if this wasn't something he even put any thought into at all.

Dean and Sam take a step back almost at the same time. "Hey Kevin, why don't you help Cas back to bed," Sam says with that perfectly reasonable voice, and okay, Kevin is the best option here, what with him being a beta and all, but it doesn't change the fact that Dean wants to strip the skin from his bones when he puts his hands on Cas' arm to tug him back down the hall.

Just as Kevin starts to lead him away he looks at him and Sam. "I don't think he has anything," Kevin says and Dean knows he's right. Shit. Cas is going to need supplies. As in toys. For Cas. For his--

Dean doesn't need to kill Kevin. He just needs to find a deep, dark hole to drop himself in. This can't be happening. Sam looks about enthused as Dean himself is about the subject.

"Can you guys take care of it?" Kevin asks, all kindness and understanding, a placating hand on Cas' arm that Dean can't tear his possessive stare away from.

"Uh... yeah, we can do that. Right, Dean?" Sam replies. And fuck, Dean can't say no because now he'd be an asshole.

"Yeah, right. Sam and I will just, uh..." He grabs Sam's arm like a lifeline and backs away towards the door. Kevin smiles and leads Cas away from the doorway and down the hall.

Like a shot from a gun Dean is out of the bunker with Sam hot on his heels. He leans against the heavy door once he's out and gulps down cool morning air, trying to clear out the overwhelming scent that is Cas in heat.

"So... motel?" Sam asks. Dean nods emphatically. There's a go bag with a few days worth of clothes for the both of them along with a wad of cash in the trunk of the impala in case shit goes down and they need to get out fast. This is exactly the time it needs to be used.

There's no way Dean can go back in there.

An hour later Dean finds himself in the omega section of some adult store trying to pick out something that will help Cas out. There's toys in every color of the rainbow, ones that are bendy, some are rigid, and there's even a few that inflate. The one he's currently holding says something about 'keeps up with even the hottest heats'. All he can think about is how the toy they choose will eventually be buried inside--

He puts the toy back and takes a few breaths, trying very hard to not think about who will be using it in a very short amount of time.

"What about this one?" Sam asks and shoves a pink monstrosity under Dean's nose. 

Dean snatches it out of Sam's hands and stuffs it back on the shelf. "Cas isn't a girl," Dean snaps. "No pink."

"But the box says-"

"Fuck what the box says," Dean interrupts.

Sam's bitch face comes out in full force. "You know, you could at least try to be more understanding. This is the first time Cas has ever had to go through this. He needs our support and understanding."

Yeah, support. Sure, Dean can be supportive. Just from far, far away where he doesn't have to smell Cas. Or know what he's likely doing, or will be doing with the toy Dean buys him.

"Let's just get him something and get the hell out of here," Dean says weakly.

Sam shakes his head and grabs another box, reading it calmly like it's completely normal for them to stand around in a sex shop reading about fake knots. They decide on a black toy that has an inflatable knot, not too big but sturdy looking. The girl at the counter smiles and looks speculatively between him and Sam, likely thinking it's for some weird, kinky alpha/alpha sex thing.

They stop off at a grocery store and pick up some sports drinks and easy to eat food. Heats and ruts always leave a body dehydrated, and there isn't much time for making extravagant meals between waves. They drop everything off at the war room table and Kevin rifles through the bag, nodding approvingly as he sorts through the stuff. Dean can still smell Cas so he tries to breathe as little as possible. Fat lot of good that does him.

"Sam and I are gonna stay at a motel in town for the next few days," Dean tells him as he grabs a few folders from the table and stuffs them in a duffel he grabbed from the trunk, and Sam is dutifully doing the same. Neither of them go down the hall to the sleeping quarters.

Kevin nods. "That's probably a good idea. I'll stay here; if he needs anything I'll text you."

Sam nods and heads for the door. "Sounds good. Thanks Kevin, we really appreciate your help, here."

Dean doesn't trust himself to speak, just nods his affirmative, breathes with his mouth and heads back out. The drive to to the motel is quiet and uneventful. He feels like his muscles are stretched too tight, feels like his head is going to explode if he tries to think about this too much.

Sam takes over the only table in the motel which leaves Dean to sprawl out on one of the beds. He spreads the paperwork he was looking over before this whole day got messed up all around him, but try as he might he can't concentrate. All he can think about is Cas, the look on his face, the brightness of his eyes and that intoxicating scent.

Dean is no fool, he knows what Cas is likely doing right now. Spread wide on his bed naked, his muscles flexing rhythmically, covered in sweat shine, slick and come. The toy they bought him most likely will be buried deep inside him and Cas would be moaning through all of it. Maybe he's riding it hard, trying to get it as deep as possible, or it's a slow grind with Cas' ass shoved up in the air and his face mashed into the pillows, making tiny little noises with each press of that toy.

Dean slaps a hand over his eyes and breathes in and out. He tries to will away the sudden raging erection trying to fight its way out of his pants. It doesn't work.

Maybe Kevin is already trying to force fluids into him. In Cas' room. Alone. Together, with a kind hand on Cas' naked shoulder.

Dean's sight blurs red. He stands and stomps to the door. "Dean, what's going on with you?" Sam asks, all bitchy confusion and concern. Dean knows he smells like crazy distressed alpha and he doesn't know how to turn it off.

"I need a drink," Dean growls. He leaves the motel and drives to the nearest bar with the intention of getting blackout drunk. At least then he won't have to think about this shit.

About half way there Dean remembers that the credit cards are still with Sam and Dean doesn't have a ton of money on hand. Dean is no lightweight when it comes to drinking, which means no blackout drunk for him tonight, but he has enough cash to get a buzz on at least.

The bartender and the other patrons give him a wide berth, which Dean doesn't appreciate. If he can't get drunk then a good old fashioned bar fight will do. But its 3pm on a Thursday and the place he's at isn't seedy enough to have the kind of people Dean knows he could pick a fight with. So.

Back to nursing his whiskey and thinking about Cas. Which he refuses to do because Cas is his friend. Friends should come before Dean thinking of them naked and writhing on a bed, presenting in beautiful submission, their ass high in the air and begging him to just take them.

Dean knows without a doubt that Cas would look gorgeous like that – if he were thinking about it, which he totally isn't. All that milky white skin stretched and glowing over taut muscle and shining with sweat with Cas moaning quietly, barely able to keep all that need under control. Cas has always been good looking. When he's fighting those strong limbs of his know exactly where and how to move, every step and motion is used to get the maximum amount of damage. Or when he's confused, his cute tilted head and squinty eyes makes Dean smile every time. Or when Cas is staring right at him. Those impossibly blue eyes stare right into his soul and it does something to Dean every single time.

Alright, so there may have been a few times Dean thought of him during some quality alone time, but so what? Everyone has their fantasies, and Dean definitely isn't a monk. It's usually under the cover of night or during a particularly hard rut that he does it. The thought of burying himself deep in that sweet, wet omega ass made Dean _want_ but he always tucks those thoughts away the moment he comes, wrapped too heavily in guilt and self loathing to really enjoy the afterglow. Dean shouldn't think of Cas like that. They're friends and brothers in arms, nothing else.

Cas hasn't given him any hints that he wants Dean that way, and Dean isn't some low brain knot head that doesn't understand when his attentions aren't wanted. So he doesn't push, and he doesn't touch, and he especially doesn't think about Cas.

Or at least he actively tries to not to think about him. Sometimes it slips through the cracks. Like right now when Cas could be doing things to himself that make Dean's mouth go dry and his cock try to push its way out of his jeans.

The sun has gone down and there's a bite in the air when Dean finally leaves the bar. He bums a smoke off some guy in the parking lot and sucks it back, floating on the head rush he gets before driving back to the motel. He drops the takeout he got on the table for Sam - some heart healthy chicken salad thing while Dean scarfs down his burger, but he barely tastes it.

When he finally climbs into bed he feels like he's run a mental marathon and sleep should come easy, but he's been tense all day and his body isn't ready for sleep. It's ready to move, ready to thrust, fuck, claim, sweat and be pushed to the edge of exhaustion, and it's really hard trying to tell his body that it just won't happen.

Damn it. Dean rolls over, ignoring his cock, his instincts and everything else he's been fixated on today. He thinks about the vamp nest Sam was researching this morning. They still don't know if it's actually vamps, but some of the police files Garth sent their way looks promising. The distraction is soothing, and eventually Dean is lulled into a fitful sleep.

***

There's a terrible noise breaking through the fog of Dean's sleep and it isn't stopping, some shrill beeping that he thinks he should recognize.

"Get the damn phone, will ya?" Sam mutters sleepily and throws a pillow at Dean.

"Gurf-" Dean replies eloquently. He blindly smacks at the bedside table, finds the creator of the terrible noise and hits a button. "This better be important," Dean mutters into his phone.

"Dean..." every hair on Dean's body stands on end and his body goes rigid. Cas' voice has always been deep, but it's deeper and threaded through with sex, panting lightly.

"Hey, you OK?" Dean asks, valiantly trying to sound like he didn't just hear Cas' sex voice.

Sam sits up in the other bed, looking concerned and mouths the word 'who?' Dean waves him back and gets out of bed.

"Dean," Cas says again, quieter but no less deep. "I'm not sure if this is normal. This need. _I need_..." Dean hears Cas swallow through a dry throat and pant softly into the phone.

All the moisture in Dean's mouth evaporates. "Don't worry, buddy, you can do this." Dean tries to project confidence into his voice, but he isn't sure how well he's doing. "Just keep on... doing what you're doing. It'll be over in two more days."

Sam's giving him the full on puppy face, the very picture of worried, concerned friend. Dean wishes he could look like that. Cas groans so deeply that it makes Dean's dick perk up and take notice, then there's some shuffling and someone else's voice raised in question which has to be Kevin. Dean tightens his hand on the phone and he clenches his jaw so tight he hears it creak.

Kevin shouldn't be in Cas' room. No one should be there but him.

"Dean? Hey its Kevin," he says and Dean tries to unclench his jaw enough to speak.

"Kevin? What's going on?" Dean snaps. Sam climbs out of bed and does a weird pointy thing at the phone. "Hold on, I'm putting you on speaker phone." Dean presses a button and the white noise of Kevin's breathing comes through the speakers.

"I think this is a pretty bad one," Kevin says. A clicking sound that Dean recognizes as a door closing makes him relax just a little, and Dean goes from clenching aggression to kicked puppy. He just feels like a guilty asshole now. Kevin is trying to help Cas and Dean really needs to remember that.

"What do you mean?" Sam asks.

"I have a theory on that," Kevin says Dean almost rolls his eyes. Of course the wonder boy has a theory. " Remember when Cas became human and he told us that he was starving and almost dying of thirst, but didn't know what those feelings were?" Dean remembers that, it was something Cas shared not all that long ago at one of their sit down meals.

"Yeah, what about it?" Dean asks.

"Well what if this is the same? What if, after years of holding off human functions his body is finally reacting to his heat the same way? Huge hunger, huge thirst..."

"Huge heat." Sam summarizes with a worried look at Dean.

Dean runs a hand through his hair and blows out a breath. "Do you think it's that bad?" Dean asks.

"Yeah, Dean, I do." Kevin confirms sadly.

"Do you think suppressants would help?" Sam asks hopefully.

"I highly doubt it. They're for before a heat hits, not after its here," Kevin replies and Dean has to agree. He vaguely remembers reading a warning on the side if a suppressant container he used when he was hunting werewolves. Dean doesn't really see the point in taking suppressants for himself outside of hunting those damn things. To be honest it makes him feel itchy and he hates how his scent changes. He'd rather take the rut than feel uncomfortable in his own skin.

"So how can we help?" Dean asks. Maybe they could go to that adult store in the morning and ask some questions from the girl behind the counter.

Kevin sighs loudly. "You're not going to like this, but I think he needs... uh, human intervention."

Dean and Sam look at each other for a moment in confusion. Sam's face quickly slides from confusion to horrified concern. Dean thinks about it for a second and his face goes hot. "You mean..." Dean says in a strangled voice.

Kevin sighs again and says quietly, "He's been asking for you, Dean"

Dean nearly drops the phone. Cas has been asking for him? As in to help him get through his heat? Dean isn’t sure how to process this. Doesn’t know if Cas understands what it means to ask for this kind of help from someone. How can Dean possibly go over there with all the things he's wanted to do to Cas over the years - _fuck, claim, bite, mine, mine, mine -_ and just make it some kind of relief fuck? He doesn't know if he can do it.

Sam looks like he knows what's going on inside Dean's head and grabs the phone from his numb fingers. "Are you really sure about this, Kevin?" Sam asks.

"Look, my girlfriend, she was an omega. I know what I'm talking about and I know what a normal heat looks like, but this?" There's a groan somewhere in the distance, pained, deep and needy. Dean's stomach drops at the sound. "I've never seen a heat like this. Nothing is helping."

Sam nods and looks at Dean with calm determination. "I'll drop Dean off. Get a bag ready, I'm pretty sure you don't want to stay there while... you know.."

"Sam!" Dean hisses. This can't be happening. Can't. Be. Happening. Yes, he wants Cas to have relief, but Dean doesn't know if he can do this. If he goes into that bunker he's worried he won't survive. If he does help Cas through this heat then it won't be guessing and fantasizing any longer, he really will know the taste of Cas' mouth and skin, the texture of his slick over Dean's fingers and the clenching heat of his body.

Sam says a few more things to Kevin and ends the call. He's standing there looking at Dean and he doesn't know if he can look back without showing Sam exactly whats running through his head.

"Sam," Dean pleads, all quiet desperation and worry.

"I can try myself if you really can't do this," Sam offers kindly. The words are barely out his mouth and Dean's whole body clenches. Sam nods like Dean's face is confirmation enough and puts a placating hand on his shoulder. "It's this or letting Cas burn," Sam tells him and grabs the keys from the table. "Grab your duffel, I'll drive you there."

They make a stop at a 24 hour convenience store to pick up a large box of knot friendly condoms, which is possibly even more awkward considering Sam is in the car and knows exactly what Dean is buying. It's either this or Cas getting pregnant though, and Dean has more than enough to deal with right now. Throwing a child into the mix wouldn't be fair to anyone, especially the kid.

They should have gotten Cas on suppressants and birth control the moment they got him back.

The hour ride back to the bunker is spent in tense silence, and Dean wants to fill it - tell Sam this is a terrible idea. Tell Kevin to get Cas into a cold shower and see if that takes his heat down a notch. Tell the whole world that a man can only be stretched so thin before he finally snaps. He doesn't, though. He sits on the passenger side and stares resolutely ahead, watching the broken yellow line get eaten by the hood of the impala as they draw ever nearer to the bunker. He can feel the weight of Sam's eyes on him from time to time, likely trying to think of something to say that will make Dean feel better about the situation. There isn't really anything to say that will make this mess any better. Sam doesn't say a word, and Dean doesn't know if he's happy about that or not.

Kevin stands from leaning on the bunker door and comes towards them with a bag in his hand looking mildly uncomfortable when they pull up. "Hey, guys," he greets with a small, tight smile that falls when he looks at Dean.

"How is he?" Sam asks, leaning over the roof of the impala.

Kevin shakes his head. "Not good. Honestly, if I thought there was another way I would've mentioned it," he says this to Dean like it's an apology.

Dean claps him on the shoulder and tries to be that stand up guy everyone wants him to be. And he is that, too, there's just a big part of him that doesn't want to do this. Wants to take and mate and claim, claim, _claim his mate_.

Dean has to fight it. He's helping his friend, not taking his mate. "I know," Dean says and steps away from the car. "Get in, Sam will take you to the motel. I'll call you guys when it's over."

Kevin's shoulders slump in relief. "Thanks, Dean."

There isn't really anything to say after that. He says a quick goodbye to the guys and turns, doesn't watch them drive off and steps into the bunker.

Dean can smell Cas' scent the moment he opens the bunker door. It was built with circulating air being a priority, and whoever designed it didn't think to cut the living quarters out of it. The Men of Letters obviously didn't have omegas in heat when they designed the place and Dean wants to curse them out for their old fashioned 'alphas only' thinking. It isn't too strong where he stands, so at least there's that - just a sweetness in the air that makes Deans mouth water. As Dean walks closer to the living quarters the scent gets stronger until it blocks everything else out and all Dean can smell is Cas.

It's doing things to him. It's making Dean's brain cloudy, his muscles tense and his cock throb.

When he gets to Cas' room and knocks on the barely open door it's missing an integral part of the whole plan. "Cas?" Dean calls out. The bed is rumpled and looks recently used but there's no one on the bed. Dean puts a hand on the sheets expecting warmth but they've gone cold.

Maybe he's gone to the bathroom to stand under a cold shower? Dean goes in search of his wayward charge, but the bathroom is just as empty and there's no condensation fogging up the mirrors. Dean stands in thought for a moment, trying to think past the haze of in heat omega. The only other place he can think of is the kitchen. Perhaps Cas is between waves and needs some food?

He's on his way to the kitchen when he stops at his bedroom door and inhales. It smells like him, but it smells a whole lot like Cas too. He pushes open the door and his brain comes to a screeching halt.

Cas is lying on his back _in Dean's bed_. He's gloriously naked and his pale skin is flushed bright and rosy from his heat. His hair, typically sticking up in every which direction is plastered to his head with sweat and his eyes are glassy and staring up at the ceiling. He tips his head back and Dean gets a good eyeful of inviting, unmated omega neck. His chest is rising and falling in heavy pants, and Dean can't stop his eyes from traveling further down where Cas has one hand wrapped loosely around his cock, and the other has his fingers thrusting rhythmically into his slick, perfect ass.

Cas presses his fingers in deeper, cants his hips up and moans _,_ then tips his head to the side and their eyes lock. Dean has had oh, so many fantasies about just this situation and he blinks a few times, wants to pinch himself because things like this don't just happen in real life.

"Dean..." Cas moans shakily as if in pain and thrusts into his hand. “I couldn't – It smells like you so I-- unh. I came here.”

Dean's shirts are off before he even registers that he's moved, like his instincts don't have time for Dean and his slow boat to China brain. "Jesus, Cas..." Dean growls. "In my bed? Fuck."

Dean's fumbling hands unbuckle his belt, it's only seconds more and then he's naked.

"It's the only place I could go that gives me relief," Cas whines, actually whines and opens his legs wider so Dean can see exactly what he's doing to himself.

But Dean doesn't want that. He doesn't want a single other person touching Cas' perfect, sweet hole.

It's his to touch and kiss and lick and claim.

"You have no idea what you look like, do you?" Dean murmurs. He climbs on the bed and knocks Cas' fingers from his hole. Cas makes a sound of protest, tries to get his fingers back inside but Dean holds him fast. Dean spreads Cas' cheeks wide, presses his nose to his taint and inhales the scent of Cas. It's strongest here and Dean feels drunk with Cas' pheromones enveloping him. He nips at his inner thigh possessively and watches the skin grow pink, then pinker from his bites, reveling in Cas crying out in need.

Dean's mouth waters at the glossy slick covering the soft, pink furl of Cas' hole. Dean gives in to his want and licks him from tailbone to balls, catching the taste of Cas on his lips. It's better than anything he could have imagined on his own - it's thick, heady and sweet, Dean could happily live off this taste alone. Dean pushes his tongue deep inside, it's even sweeter here and he groans so deep he can feel it in his bones.

"Oh my-- unh," Cas grunts and fists his hands in Dean's hair to pull him closer. Cas is hot everywhere, fever-hot, not just heat-hot and Dean gets why Cas and Kevin asked for his help. He doesn't think much more on the subject though because this, this right here is where Dean should _live -_ with his tongue so deep inside Cas that he can lick up every drop of slick that leaks out until he can't make anymore.

"Please..." Cas begs. His hand goes to his cock, fists it hard and fast and Dean has a front row seat to how Cas gets himself off. He pulls off his hole to slide two fingers in and Cas cries out and doubles his efforts.

"C'mon, Cas. Give it up. Wanna see you give it up to me," Dean growls. "C'mon, baby, make yourself come on my fingers."

Cas arches his back and gasps, looking sightlessly up. His forehead is wrinkled in deep concentration, and Dean thinks he'll get there, he just needs a little more help. Dean pushes his fingers in deeper, twists and curls them up, finding the bump Dean is looking for and presses hard over and over again.

"There!" Cas cries out, his entire body locks up and his muscles clamp down impossibly hard on Dean's fingers. String after string of come stripes Cas' chest and belly and it's like someone reaches up just under Dean's balls and wrenches something deep inside him. Dean is suddenly so close to popping a knot it's really not funny.

"Holy shit, Cas, you're gorgeous like this," Dean mutters. He's sweating and knows he's done for. He doesn't know how much longer he can wait to slide into that perfect clenching heat.

But this is Cas' first heat and he wants to at least try to make it good for him. Dean slides his fingers out of Cas' now limp body and climbs up and over until he finds the slick of come across his belly. Dean licks Cas up until there's nothing left. He's salty here, more musk than sweet and Dean likes the contrast, wants more, more, _more_.

"Dean," Cas moans, and Dean kisses higher, finds a nipple and sucks. Cas' hands tighten in his hair again, softer this time but no less hot.

"Tell me what you need, Cas," Dean murmurs against too hot skin. Licks his way to the other nipple and gives it the same treatment.

"You," Cas sighs and arches, pressing his chest into Dean's mouth. Dean starts to use his teeth, worrying the little nub of flesh back and forth. "Always you. Damn it, Dean."

Dean pulls off and lies fully on top of Cas, and Cas' legs move to bracket Dean's hips. "I need to hear you say it. Say it, Cas." Dean orders.

He wants to know that this isn't just biological imperative. That he's here for a reason other than Cas' heat. He could have asked for Sam, could have found assistance from Kevin too. But it's Dean he asked for. _Dean_. And he needs to hear Cas say it.

Cas looks utterly wrecked, his lips are pink and swollen, bitten red in some places, his forehead is bright with perspiration and his cheeks are flushed, but his eyes are serious, far more so than Dean finds comfortable. "I need you, Dean. I need it. You. All of you. I need your knot, alpha."

Fuck. Dean wasn't expecting that. It feels like his blood is boiling in his veins from that statement alone. The honesty and desperation in those words break him apart. "Then you'll have it. You'll have me, omega."

As first kisses go Dean's had better, he's been better too but they've never felt like this before. As if the world just slotted into place, like Dean was lost and now is found. Like every road he's ever driven has been leading him to this exact moment. To his home.

There's a clashing of teeth and then Dean's inside Cas' mouth, licking possessively into it. Cas is _his_. No one else's and he will be god damned if anyone tries to touch Cas, whether it be during a heat or otherwise after this. He lays claim to every space, bites down on his lush bottom lip, swallows down Cas' moan and keeps kissing. He gets a hand on Cas' nape and presses him closer, trails his thumb over that soft space right behind Cas' ear and when the kiss ends he realizes that he was growling. Actually growling into Cas' mouth the whole time.

Cas looks like someone just shook him up right to his soul, looks shell shocked, amazed and a little bit wondrous. "Dean?" He asks in a small voice, and Dean presses their foreheads together.

"I know, Cas," Dean replies to the unasked question and runs a hand through Cas' hair, trying to soothe away the trembling in the other man's limbs. He knew that he and Cas were compatible just from Cas' scent but Dean wasn't expecting this, and by the looks of it neither was Cas. It isn't just Cas that's trembling, Dean is too - a fine tremor in his hands that Dean can't stop no matter how he tries.

Dean is supposed to be here to help his friend get through a rough heat. He isn't supposed to find the answer his soul has been asking the question of since he was born. Damn it, he doesn't know what that question even is.

This right here is the real reason Dean stays away from omegas. Finding a mate doesn't fit into the life he has. It isn't fair to get attached to someone when he lived out of his car for most of his life. They've only barely put down tentative roots and it's in a 1950's war bunker that could withstand the frigging apocalypse. That isn't how normal people live. His life isn't normal and Dean's OK with that, he hasn’t been looking for anyone because it wouldn't be fair to either him or his mate.

But now? He doesn't know. And what really scares him is that he isn't sure if he can deny this gorgeous creature that's squirming under him. Doesn't think he could say no to Cas if he asked.

What he can do, however is say yes to helping him. He can help his friend get some relief. Dean will just have to keep himself in check. He kisses Cas again, backs up to grab a condom from his pants pocket and rolls it on. Cas looks somewhere between desperate and vulnerable, and Dean comes back to him, kisses his cheek, the tip of his nose, his plump bottom lip. Runs his hands soothingly over too hot skin.

"You still with me?" Dean asks.

Cas shakes his head and swallows hard. "Not like this, please, I need..." Cas moves out from under him, gets his knees on the mattress and fucking _presents_. And there goes Dean and his fanciful ideas of self control. He has officially reached his breaking point.

Dean follows his instincts, spreads Cas' ass cheeks, gets a perfect view of wet, sweet omega hole, lines up and pushes in right to the root in one hard, unrelenting shove.

Hot. Searingly hot, so tight and beyond perfection. That's what being inside Cas is like. Cas hisses through his teeth like it's the best and worst feeling he's ever had, arches his back like a cat and tries to fuck himself on Dean's dick. "I got you, Cas," Dean tells him, wraps his hands around Cas' hips and takes over. He fucks Cas hard, a primal, insistent pace and with each thrust Dean claims him. Wipes away anyone who may have tried to stake their claim on him before with each inward stroke.

This is his now. This boiling wet clenching paradise. No one else's. Dean curls forward, gets a hand low on Cas' belly and licks the side of his neck. It's salt and sweetness, heat, wetness and everything Dean could hope for. The taste and smell of this moment is burned into his sense memory, he knows he'll remember this until his dying day.

Cas is gasping and grunting with each thrust, matching Dean's pace with a ferocity Dean has seldom seen from him outside of hunts and battles, and it spurs Dean on. He changes his angle, makes Cas arch just that little bit more and Cas cries out when Dean fucks so deep he hits something Dean suspects might be his cervix.

Cas' hands clench white knuckle tight on the bed spread and his head snaps back. "Fuck! Yes, there!" He yells. Dean can count on one hand how many times he's heard Cas swear. It's always sounded stilted and stiff coming from the former angels mouth, but this is the first time it doesn't sound off, like Cas' mouth formed the words before he even thought them. Cas braces a hand on the headboard and growls.

Dean's sweating and he can feel his knot start to swell. It catches each time he thrusts in, making a wet sound with every thrust. Cas is grunting, crying out with each thrust and Dean's breathing heavy and hard like he's run a five minute mile.

And he never wants it to stop.

Dean's knot is filling and swelling and he knows he can't last much longer. He can feel from the rigid length of Cas' cock as it brushes against Dean's hand still sitting low on his belly that Cas isn't far behind. Dean grinds in, fucks into Cas with short hard strokes so deep inside the other man that Dean wonders if he can feel it against his hand, wonders if he pressed just so could he feel the effect of his cock deep inside the other man.

Cas is almost sobbing, it sounds like he's trying to say something but the words won't come out. He tries to move somewhere, maybe get a better grip, but Dean is too far gone. He presses his weight onto Cas' chest, sets his teeth on Cas' neck right at the join between neck and shoulder and grinds in hard as his knot fully pops.

It's only with the barest grip on himself that Dean doesn't bite down.

"Do it!" Cas yells and fucking _moves to bare more of his neck_. "Do it, bite me!"

Dean can't fight this. He can't fight his instincts and Cas too, not when they all want the same thing. Suddenly all the reasons to not claim what's already his doesn't seem to matter any longer - are drowned out by the Cas shaped hole in his chest that can only be filled one way. Dean squeezes his eyes shut, bites down hard and comes.

He's vaguely aware of Cas clenching around him like a vice when he comes. Of him yelling out in completion and pain as Dean breaks skin with his teeth, but its all secondary, like peripheral vision. It's there, but not in the forefront.

What he does know is suddenly Dean feels _whole_. Not pretending and not convincing himself whole. Not drunk so it isn't there and not hiding either. It just is. He's complete and when he convulses as another wave of come shoots out of him he growls deep and dark because it's the only sound he can make.

With the last shred of his working mind Dean turns them on their sides and then he's lost. Floating and serene on the endorphins of their mating.

It's by slow increments that Dean returns to himself. There's the feeling of warm skin pressed all along his front, of Cas clenched perfectly around his knot. The slow, heavy thump of Cas' heartbeat against his chest, steady as a metronome. The smell of slick, come, sweat and pheromones, of temporarily sated omega heat is thick in his nose. The taste of salt and slick sits at the back of Dean's mouth and there's a sharp tang of copper pennies over all of it.

Dean opens his eyes slowly and stares at Cas' neck. He feels a hand trace over his forearm and down to link their hands that's still sitting low on Cas' belly.

Dean leans in and scents Cas. He knows it's ridiculous to think the change would be instantaneous. It will take a good 24 hours for Cas' scent to change. Cas moves to bear more of his neck and Dean sees the full extent of his actions.

Two crescent moons, little indents that match his teeth perfectly sit at the curve between neck and shoulder. If Cas were to wear a collared shirt just the barest edge would be seen. It's still bleeding a little and it's already red around the edges, a promise that it will bruise a little in the coming few hours.

Dean licks it clean, then traces over it with his eyes. A mating bite. On Cas. His brain is starting to spark online, and the endorphins running through his system quiet down with the realization of what Dean has done.

He wasn't supposed to do this. Wasn't supposed to tie Cas to him this way. Dean's done a lot of stupid shit in his life, but he's always prided himself on not mating any available omega with a hole that offers themselves to him. He's gone his entire life without biting anyone there. Now he has and it changes everything.

"Dean?" Cas asks, quiet and soft like he's still floating.

Dean closes his eyes, hides away from the mark and presses his forehead to the back of Cas' shoulder. "Sorry, Cas." He replies in an equally quiet voice.

Cas' turns his head closer to Dean. "For what?" He asks, and there's curiosity there, like he really doesn't understand why Dean's apologizing. There's a lump in his throat that Dean's voice can't get past. He just shakes his head and traces slow, gentle fingers over his mark on Cas.

"Oh," Cas says softly, and Dean can hear the disappointment in his voice. "Then I. Um. I should apologize too."

Dean snorts. Cas has done nothing - absolutely _nothing_ wrong. "You're fine, Cas. I just. I didn't mean to, uh..." Dean swallows. "I guess you're stuck with me now," he ends lamely with a chuckle but it sounds far too sad to his ears to really be called that.

Dean watches Cas run careful fingers over the mark, tentative yet graceful. "It's alright," he says with an odd note of humor that he must have picked up from Sam. "We were already stuck together. This just makes it... more."

There's a smile in Cas' voice and Dean wants to turn him around, shake him, tell Cas what a monumental fuck up Dean is. That no one can be around him for very long without dying and he's so very scared that he'll lose Cas just like he has with so many other friends and family. Wants to tell him that Dean doesn't deserve this gift. Other people get a house and a mate and a white picket fence, not him. He's terrified for what this means and who they are to each other now. Cas will be even more of a target than he already is and Dean hates that he's put this man in the cross hairs yet again.

Cas takes in his silence and the distress coming off him. His his shoulders tense and Dean can smell Cas' distress start to rise up. "I'm sorry, Dean. When I asked you to... I thought it would be something you wanted as well."

The thing of it is, Dean _does_ want it. Wants to have Cas in his arms and his bed, just like this for the rest of their lives. He tries so hard not to be a selfish man - he thinks about the kind of person Cas needs as a mate, and he comes up short. Dean's been through too much, been broken too many times. He just doesn't deserve this wonderful, quirky, amazing person curled up next to him for the rest of eternity. Besides, people say and do some weird shit when they're about to come. "People yell out all kinds of stuff in bed, Cas. A lot of it people don't mean."

"Well _I_ meant it." The truth of Cas' words, simple, direct and without any sarcasm or evasion strikes something deep in Dean. Cas' hand covers over his mark, cups it under his (fragile, mortal, breakable) human palm, then starts to slide away. "I never meant you to do something you dislike. I can repudiate it if you--"

"No!" Dean yelps and covers Cas' hand with his, their mating mark nestled safely below. The words are barely out of Dean's mouth and his body curls more tightly around Cas. He wasn't prepared for the onslaught of mine, mate, forever when Cas said those words. He doesn't want Cas to reject his mark. Just thinking about it feels like he'd be losing something akin to a limb.

"You're mine, Cas," Dean promises. His hand slides away from their mark and down smooth, supple skin to rest over the center of Cas' chest, pulling him more tightly into the curve of Dean's body. The movement jars his knot where it's still buried hot and safe inside Cas, and Dean moans as another load of come fills him. "Mine," Dean repeats, as if he can seal them together more tightly with words alone.

"Yours," Cas nods, and relaxes into Dean's embrace. He sighs and goes completely limp and it does things to Dean's brain knowing that Cas is still, that he's submitting so Dean can claim him (his mate, his) inside and out. He groans deep and grinds into him, like Dean could somehow get deeper and buries his nose in Cas' neck, scenting his relaxed, trusting scent.

They stay just like that until Dean's knot goes down and slips from Cas. He barely has the brain power to chuck the condom and get some fluids in them before he's passed out with Cas' head resting on his shoulder, a leg wedged between his.

 

**Author's Note:**

> Thank you lovelies for reaching the end! I'm thinking this may need a sequel but I'm honestly not sure because this fic feels pretty good as a stand alone. Please let me know your thoughts, I'd love to hear from you!
> 
> I'm also open to concrit. How else am I gonna get better, right?


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